X-rays are not used for radar purposes, because they are not 

(1) reflected by target

(2) partly absorbed by the target

(3) electromagnetic waves

(4) completely absorbed by the target

The energy of the X-rays photon is 3.3$\times {10}^{-16}$J. Its frequency is :

(1) $2\times {10}^{19} Hz$

(2) $5\times {10}^{18} Hz$

(3) $5\times {10}^{17} Hz$

(4) $5\times {10}^{16} Hz$

A plane electromagnetic wave

$E_z=100 \cos (6\times {10}^{8}t+4x) V/m$

propagates in a medium of dielectric constant

(1) 1.5

(2) 2.0

(3) 2.4

(4) 4.0

The magnetic field between the plates of radius 12 cm separated by a distance of 4 mm of a parallel plate capacitor of capacitance 100 pF along the axis of plates having conduction current of 0.15 A is

(1) zero

(2) 1.5 T

(3) 15 T

(4) 0.15 T

A larger parallel plate capacitor, whose plates have an area of 1 $m^2$, separated from each other by 1 mm, is being charged at a rate of 25.8 V/s. If the plates have dielectric constant 10, then the displacement current at this instant is:

1. 25 $\mu A$

2. 11 $\mu A$

3. 2.2 $\mu A$

4. 1.1 $\mu A$

A parallel plate capacitor with plate area \(A\) and separation between the plates \(d\), is charged by a source having current \(i\) at some instant. Consider a plane surface of area \(A/2\) parallel to the plates and drawn symmetrically between the plates. The displacement current through this area is:
1. \(i\) 
2. \(i/2\) 
3. \(i/4\) 
4. \(i/8\)

The sun delivers ${10}^{3}W/m^2$ of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimensions 8 m$\times$20 m will be:

1. $2.56\times {10}^4$ $W$

2. $6.4\times {10}^5$ $W$

3. $4.0\times {10}^5$ $W$

4. 1.6$\times {10}^5$ $W$

In a region of free space, the electric field at some instant of time is $\overrightarrow{E}=(80\hat{i}+32\hat{j}-64\hat{k})$V/m and the magnetic field is $\overrightarrow{B}=(0.2\overrightarrow{i}+0.08\hat{j}+0.29\hat{k})\mu T$. The Poynting vector for these fields is

(1) $-11.52\hat{i}+28.8\hat{j}$

(2) $-28.8\hat{i}+11.52\hat{i}$

(3) $28.8\hat{i}-11.52\hat{j}$

(4) $11.52\hat{i}-28.8\hat{j}$

A plane electromagnetic wave propagating in the x-direction has wavelength of 60 mm. The electric field is in the y-direction and its maximum magnitude is 33 V/$m^{-1}$. The equation for the electric field as function of x and t is

(1) 11 sin $\mathrm{\pi }$(t - x/c)

(2) 33 sin $\mathrm{\pi }\times {10}^{10}$ (t - x/c)

(3) 33 sin $\mathrm{\pi }$(t - x/c)

(4) 11 sin $\mathrm{\pi }\times {10}^{11}$(t - x/c)

In an electromagnetic wave, if the electric field oscillated sinusoidally with an amplitude of 48 V$m^{-1}$, then the RMS value of the oscillating magnetic field will be:

1. $1.6\times {10}^{-8}$ $T$

2. $1.6\times {10}^{-9}$ $T$

3. $144\times {10}^{-8}$ $T$

4. $11.3\times {10}^{-8}$ $T$